Organic light-emitting display apparatus

ABSTRACT

An organic light-emitting display apparatus for selectively realizing circular polarization according to external light conditions, including a substrate; an organic light-emitting device on the substrate; a sealing member on the organic light-emitting device; a phase retardation layer on a surface of the substrate, the organic light-emitting device, or the sealing member; and a linear polarization layer on another surface of the substrate, the organic light-emitting device, or the sealing member, wherein the linear polarization layer is located to be closer to a source of external light than the phase retardation layer, and wherein the linear polarization layer comprises a photochromic material.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This application claims priority to and the benefit of Korean PatentApplication No. 10-2010-0051442, filed on May 31, 2010, in the KoreanIntellectual Property Office, the entire content of which isincorporated herein by reference.

BACKGROUND

1. Field

The following description relates to organic light-emitting displayapparatuses, and more particularly, to organic light-emitting displayapparatuses for selectively realizing circular polarization according toexternal light conditions.

2. Description of Related Art

An organic light-emitting display apparatus uses a circular polarizationfilm for improving the contrast thereof under an external lightenvironment such as sunlight.

A liquid crystal display (LCD) apparatus uses a polarization film, butan organic light-emitting display apparatus uses a circular polarizationfilm as a main component for realizing an image. When the circularpolarization film is used in order to prevent or reduce external lightfrom being reflected, the brightness of the organic light-emittingdisplay apparatus is reduced by at least 50%.

In particular, in situations where the reflection of external light haslimited effect on the visibility of an organic light emitting displayapparatus, such as indoors or at night, a reduction in brightness isserious while visibility is only slightly improved by a circularpolarization film.

SUMMARY

An aspect of an embodiment of the present invention is directed towardorganic light-emitting display apparatuses for selectively realizingcircular polarization according to external light conditions.

An embodiment of the present invention provides an organiclight-emitting display apparatus including a substrate; an organiclight-emitting device on the substrate; a sealing member on the organiclight-emitting device; a phase retardation layer on a surface of thesubstrate, the organic light-emitting device, or the sealing member; anda linear polarization layer formed on another surface of the substrate,the organic light-emitting device, or the sealing member. Here, thelinear polarization layer is located to be closer to a source ofexternal light than the phase retardation layer, and the linearpolarization layer includes a photochromic material.

The linear polarization layer may be on the substrate, the phaseretardation layer may be on the linear polarization layer, and theorganic light-emitting device may be on the phase retardation layer.

The phase retardation layer may be on the substrate, the organiclight-emitting device may be on the phase retardation layer, and thelinear polarization layer may be on the surface of the substrateopposite to the surface of the substrate on which the phase retardationlayer is located.

The phase retardation layer and the linear polarization layer may besequentially arranged in the stated order on the surface opposite to thesurface of the substrate on which the organic light-emitting device islocated.

The phase retardation layer may be on the organic light-emitting device,and the linear polarization layer may be on the phase retardation layer.

The organic light-emitting display apparatus may further include aprotective layer on the organic light-emitting device, the phaseretardation layer may be on the protective layer, and the linearpolarization layer may be on the phase retardation layer.

The organic light-emitting display apparatus may further include aprotective layer on the organic light-emitting device, the phaseretardation layer may be between the organic light-emitting device andthe protective layer, and the linear polarization layer may be on theprotective layer.

The organic light-emitting display apparatus may further include areflective layer interposed between the substrate and the organiclight-emitting device, the phase retardation layer may be between thereflective layer and the organic light-emitting device, and the linearpolarization layer may be on the organic light-emitting device.

The sealing member may be a transparent substrate, and the phaseretardation layer and the linear polarization layer may be sequentiallyarranged in the stated order on the surface of the sealing memberopposite to the surface of the sealing member, which faces the organiclight-emitting device.

The sealing member may be a transparent substrate, the phase retardationlayer may be on the surface of the sealing member, which faces theorganic light-emitting device, and the linear polarization layer may beon the surface of the sealing member opposite to the surface of thesealing member, on which the phase retardation layer is located.

The sealing member may be a transparent substrate, the linearpolarization layer may be on the surface of the sealing member, whichfaces the organic light-emitting device, and the phase retardation layermay be on a surface of the linear polarization layer, which faces theorganic light-emitting device.

The phase retardation layer may include a quarter-wave plate or ahalf-wave plate.

The linear polarization layer may include a plurality of wire grids thatare spaced apart from each other.

According to an aspect of an embodiment of the present invention, sincethe wire grids constituting the linear polarization plate areselectively discolored or become transparent, according to externallight conditions, the contrast of the organic light-emitting displayapparatus is increased under sunlight, and a reduction in the brightnessof the organic light-emitting display apparatus is prevented or reducedin the outdoors or at night.

In addition, according to an aspect of an embodiment of the presentinvention, since each layer may be formed without an adhesive layer, thethickness of the organic light-emitting display apparatus may bereduced.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, together with the specification, illustrateexemplary embodiments of the present invention, and, together with thedescription, serve to explain the principles of the present invention.

FIG. 1 is a cross-sectional view of an organic light-emitting displayapparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a more detailed example of a linearpolarization layer according to FIG. 1.

FIGS. 3 and 4 are cross-sectional views of bottom-emission type organiclight-emitting display apparatuses according to embodiments of thepresent invention.

FIGS. 5-11 are cross-sectional views of top-emission type organiclight-emitting display apparatuses according to embodiments of thepresent invention.

FIGS. 12 and 13 are cross-sectional views of bottom-emission typeorganic light-emitting display apparatuses of an active matrix (AM)type, according to embodiments of the present invention.

FIG. 14 is a cross-sectional view of a top-emission type organiclight-emitting display apparatus of an AM type, according to anotherembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following detailed description, only certain exemplaryembodiments of the present invention are shown and described, by way ofillustration. As those skilled in the art would recognize, the inventionmay be embodied in many different forms and should not be construed asbeing limited to the embodiments set forth herein. Also, in the contextof the present application, when a first element is referred to as being“on” a second element, it can be directly on the second element or beindirectly on the second element with one or more intervening elementsinterposed therebetween. Like reference numerals designate like elementsthroughout the specification.

FIG. 1 is a cross-sectional view of an organic light-emitting displayapparatus according to an embodiment of the present invention.

Referring to FIG. 1, the organic light-emitting display apparatusaccording to the present embodiment includes a substrate 1 formed of atransparent material, and a linear polarization layer 2, a phaseretardation layer 3, and an organic light-emitting device 5 which aresequentially arranged in the stated order on the substrate 1. Althoughnot illustrated, a sealing member for sealing the organic light-emittingdevice 5 from the outside, such as a glass, a thin film member, or ametal cap, may be on the organic light-emitting device 5.

The substrate 1 may be a substrate formed of a transparent glassmaterial containing SiO₂ as a main component. A buffer layer may also beon the substrate 1 to smoothen the substrate 1 and to prevent or reducethe penetration of impurities, and may be formed of SiO₂ and/or SiNx.The substrate 1 is not limited thereto. Alternatively, the substrate 1may be formed of a transparent plastic material.

The linear polarization layer 2 is on the substrate 1, and the phaseretardation layer 3 is on the linear polarization layer 2. The organiclight-emitting device 5 is on the phase retardation layer 3. The linearpolarization layer 2 and the phase retardation layer 3 are arranged sothat the linear polarization layer 2 may be located to be closer to asource of external light than the phase retardation layer 3, and thephase retardation layer 3 may be on the linear polarization layer 2.Another light-transmission layer may be interposed between the linearpolarization layer 2 and the phase retardation layer 3.

The organic light-emitting device 5 includes a first electrode layer 51and a second electrode 53, which face each other, and includes anemissive layer 52 interposed between the first electrode layer 51 andthe second electrode layer 53.

The first electrode layer 51 may be formed of a transparent conductivematerial, and may be formed of, for example, indium tin oxide (ITO),indium zinc oxide (IZO), In₂O₃, and ZnO. In addition, the firstelectrode layer 51 may be formed with a preselected or predeterminedpattern by using a photolithography method. When the organiclight-emitting display apparatus is a passive matrix (PM) type, thefirst electrode layer 51 may be formed in a stripe pattern with apreselected or predetermined interval. When the organic light-emittingdisplay apparatus is an active matrix (AM) type, the first electrodelayer 51 may be formed to correspond to a pixel. In the case of the AMtype organic light-emitting display apparatus, a pixel circuit layerincluding at least one TFT may be on the substrate 1 below the firstelectrode layer 51. The first electrode layer 51 is electricallyconnected to the pixel circuit layer. Such PM and AM type organiclight-emitting display apparatuses according to embodiments of thepresent invention will be described in more detail below.

The first electrode layer 51, formed as a transparent electrode, may beconnected to an external terminal, and may function as an anode.

The second electrode layer 53 may be on the first electrode layer 51,and may be a reflective electrode. In addition, the second electrodelayer 53 may be formed of aluminum (Al), silver (Ag), and/or calcium(Ca), and may be connected to a second external terminal so as tofunction as a cathode.

In the case of a PM type organic light-emitting display apparatus, thesecond electrode layer 53 may be formed to extend in a stripe patternalong a direction that is perpendicular to the extension direction ofthe stripe pattern of the first electrode layer 51. In the case of an AMtype organic light-emitting display apparatus, the second electrodelayer 53 may be formed to correspond to a pixel. In this case, thesecond electrode layer 53 may be on an entire portion of an activeregion on which an image is realized, which will be described in moredetail.

The first electrode layer 51 and the second electrode layer 53 may haveopposite polarities.

The emissive layer 52 interposed between the first electrode layer 51and the second electrode layer 53 emits light by electrically drivingthe first electrode layer 51 and the second electrode layer 53. Theemissive layer 52 may be formed of a low molecular weight organicmaterial or a high molecular weight organic material.

When the emissive layer 52 is a low molecular weight organic film formedof a low molecular weight organic material, a hole transport layer (HTL)and a hole injection layer (HIL) are stacked in a direction towards thefirst electrode layer 51, and an electron transport layer (ETL) and anelectron injection layer (EIL) are stacked in a direction towards thesecond electrode layer 53, with respect to an organic emission layer(EML). If necessary, various other layers may be formed in addition tothe HIL, the HTL, the ETL, and the EIL.

Examples of organic materials that may be used to form the emissivelayer 52 include any of various suitable materials such as copperphthalocyanine (CuPc), N,N′-di(naphthalene-1-yl)-N,N′-diphenyl-benzidine(NPB), and tris-8-hydroxyquinoline aluminum (Alq3).

When the emissive layer 52 is a high molecular weight organic filmformed of a high molecular weight organic material, only a HTL may bedisposed in a direction towards the first electrode layer 51 withrespect to an organic EML. In this case, the HTL may be formed ofpoly-(2,4)-ethylene-dihydroxy thiophene (PEDOT), polyaniline (PANI), orthe like, and may be formed on the first electrode layer 51 by using aninkjet printing method or a spin coating method. In addition, theorganic EML may be formed of polyphenylenevinylene (PPV), Soluble PPV's,Cyano-PPV, polyfluorene, or the like, and may be formed to have a colorpattern by using a common method, such as an inkjet printing method, aspin coating method, and/or a heat transfer method that uses a laser.

According to an embodiment of the present invention, as shown in FIG. 1,light emitted from the emissive layer 52 of the organic light-emittingdevice 5 is emitted towards the substrate 1, and a user views an imagebelow the substrate 1, that is, below a lower portion of the substrate1. In such a bottom-emission type organic light-emitting displayapparatus, external light, such as sunlight, may be introduced throughthe substrate 1, thereby reducing the contrast of the organiclight-emitting display apparatus.

However, according to the present embodiment, the linear polarizationlayer 2 and the phase retardation layer 3 may constitute a circularpolarization layer, thereby preventing or reducing external light frombeing reflected. In one embodiment, the phase retardation layer 3 may bea quarter-wave plate.

Of external light from outside of the lower portion of the substrate 1,a component in an absorption-axis direction of the linear polarizationlayer 2 is absorbed, and a component in a transmission-axis direction ofthe linear polarization layer 2 is transmitted. The component in thetransmission-axis direction is converted into circularly polarized lightthat rotates in one direction while transmitting through the phaseretardation layer 3, and then is reflected by the second electrode layer53. When reflected, the circularly polarized light that rotates in theone direction is converted into circularly polarized light that rotatesin an opposite direction, and the circularly polarized light thatrotates in the opposite direction is converted into linearly polarizedlight that is polarized in a direction perpendicular to an originaltransmission axis while transmitting through the phase retardation layer3. Thus, since the linearly polarized light is absorbed by an absorptionaxis of the linear polarization layer 2, the linearly polarized light isnot emitted out of the lower portion of the substrate 1, therebypreventing or reducing external light from being reflected and furtherimproving the contrast of the organic light-emitting display apparatus.

Since the linear polarization layer 2 and the phase retardation layer 3are on the substrate 1, an adhesive layer is not located between thelinear polarization layer 2 and the phase retardation layer 3, and thusthe thickness of the organic light-emitting display apparatus may bereduced. In addition, since an image emitted from the emissive layer 52is not transmitted through an adhesive layer, the brightness of theorganic light-emitting display apparatus may be increased.

FIG. 2 is a cross-sectional view of a more detailed example of thelinear polarization layer 2.

The linear polarization layer 2 includes a plurality of wire grids 21that are on the substrate 1 with a preselected or predetermined intervaltherebetween. The wire grids 21 may each have a width of several tens ofnanometers (nm), and may be spaced by an interval of several tens toseveral hundreds of nanometers (nm).

According to the present embodiment, the wire grids 21 may be formed ofa photochromic material.

The photochromic material may be a naphthopyran-based compound, aspirooxazine-based compound, or a spiropyran-based compound, but is notlimited thereto.

Examples of the spiropyran-based compound may include1′,3′,3′-trimethylspiro(2H-1-benzopyran-2,2′-indoline),1′,3′,3′-trimethylspiro-8-nitro(2H-1-benzopyran-2,2′-indoline),1′,3′,3′-trimethyl-6-hydroxyspiro(2H-1-benzopyran-2,2′-indoline),1′,3′,3′-trimethylspiro-8-methoxy(2H-1-benzopyran-2,2′-indoline),5′-chloro-1′,3′,3′-trimethyl-6-nitrospiro(2H-1-benzopyran-2,2′-indoline),6,8-dibromo-1′,3′,3′-trimethylspiro(2H-1-benzopyran-2,2′-indoline),6,8-dibromo-1′,3′,3′-trimethylspiro(2H-1-benzopyran-2,2′-indoline),8-ethoxy-1′,3′,3′,4′,7′-pentamethylspiro(2H-1-benzopyran-2,2′-indoline),5′-chloro-1′,3′,3′-trimethylspiro-6,8-dinitro(2H-1-benzopyran-2,2′-indoline),3,3-diphenyl-3H-naphtho-(2, 1-13)pyran,1,3,3-triphenylspiro[indoline-2,3′-(3H)-naphtho(2,1-b)pyran],1-(2,3,4,5,6-pentamethylbenzyl)-3,3-dimethylspiro[indoline-2,3′-(3H)-naphtho(2,1-b)pyran],1-(2-methoxy-5-nitrobenzyl)-3,3-dimethylspiro[indoline-2,3′-naphtho(2,1-b)pyran],1-(2-nitrobenzyl)-3,3-dimethylspiro[indoline-2,3′-naphtho(2,1-b)pyran],1-(2-naphthylmethyl)-3,3-dimethylspiro[indoline-2,3′-naphtho(2,1-b)pyran],1,3,3-trimethyl-6′-nitro-spiro[2H-1-benzopyran-2,2′-(2H)-indole], or thelike.

Examples of the spirooxazine-based compound may include1,3,3-trimethylspiro[indoline-2,3′-(3H)naphtho(2,1-b)(1,4)oxadine],5-methoxy-1,3,3-trimethylspiro[indoline-2,3′-(3H)naphtho(2,1-b)(1,4)oxadine],5-chloro-1,3,3-trimethylspiro[indoline-2,3′-(3H)naphtho(2,1-b)(1,4)oxadine],4,7-ethoxy-1,3,3-trimethylspiro[indoline-2,3′-(3H)naphtho(2,1-b)(1,4)oxadine],5-chloro-1-butyl-3,3-dimethylspiro[indoline-2,3′-(3H)naphtho(2,1-b)(1,4)oxadine],1,3,3,5-tetramethyl-9′-ethoxyspiro[indoline-2,3′-(3H)naphtho(2,1-b)(1,4)oxadine],1-benzyl-3,3-dimethylspiro[indoline-2,3′-(3H)naphtho(2,1-b)(1,4)oxadine],1-(4-methoxybenzyl)-3,3-dimethylspiro[indoline-2,3′-(3H)naphtho(2,1-b)(1,4)oxadine],1-(2-methylbenzyl)-3,3-dimethylspiro[indoline-2,3′-(3H)naphtho(2,1-b)(1,4)oxadine],1-(3,5-dimethylbenzyl)-3,3-dimethylspiro[indoline-2,3′-(3H)naphtho(2,1-b)(1,4)oxadine],1-(4-chlorobenzyl)-3,3-dimethylspiro[indoline-2,3′-(3H)naphtho(2,1-b)(1,4)oxadine],1-(4-bromobenzyl)-3,3-dimethylspiro[indoline-2,3′-(3H)naphtho(2,1-b)(1,4)oxadine],1-(2-fluorobenzyl)-3,3-dimethylspiro[indoline-2,3′-(3H)naphtho(2,1-b)(1,4)oxadine],1,3,5,6-tetramethyl-3-ethylspiro[indoline-2,3′-(3H)pyride(3,2-f)(1,4)benzooxadine],1,3,3,5,6-pentamethylspiro[indoline-2,3′-(3H)pyride(3,2-f)(1,4)-benzooxadine],6′-(2,3-dihydro-1H-indole-1-yl)-1,3-dihydro-3,3-dimethyl-1-propyl-spiro[2H-indole-2,3′-(3H)naphtho(2,1-b)(1,4)oxadine],6′-(2,3-dihydro-1H-indole-1-yl)-1,3-dihydro-3,3-dimethyl-1-(2-methylpropyl)-spiro[2H-indole-2,3′-(3H)naphtho(2,1-b)(1,4)oxadine],1,3,3-trimethyl-1-6′-(2,3-dihydro-1H-indole-1-yl)spiro[2H-indole-2,3′-(3H)naphtho(2,1-b)(1,4)oxadine],1,3,3-trimethyl-6′-(1-piperidyl)spiro[2H-indole-2,3′-(3H)naphtho(2,1-b)(1,4)oxadine],1,3,3-trimethyl-6′-(1-piperidyl)-6-(trifluoromethyl)spiro[2H-indole-2,3′-(3H)naphtho(2,1-b)(1,4)oxadine],1,3,3,5,6-pentamethyl-spiro[2H-indole-2,3′-(3H)naphtho(2,1-b)(1,4)oxadine],or the like.

Examples of the naphthopyran-based compound may include3,3-diphenyl-3H-naphtho(2,1-b)pyran,2,2-diphenyl-2H-naphtho(1,2-b)pyran,3-(2-fluorophenyl)-3-(4-methoxyphenyl)-3H-naphtho(2,1-b)pyran,3-(2-methyl-4-methoxyphenyl)-3-(4-ethoxyphenyl)-3H-naphtho(2,1-b)pyran,3-(2-furyl)-3-(2-fluorophenyl)-3H-naphtho(2,1-b)pyran,3-(2-thienyl)-3-(2-fluoro-4-methoxyphenyl)-3H-naphtho(2,1-b)pyran,3-[2-(1-methylpyrrolyl)]-3-(2-methyl-4-methoxyphenyl)-3H-naphtho(2,1-b)pyran,spiro [bicyclo(3.3.1)nonane-9,3′-3H-naphtho(2,1-b)pyran],spiro[bicyclo(3.3.1)nonane-9-2′-3H-naphtho(2,1-b)pyran],4-[4-[6-(4-morphonyl)-3-phenyl-3H-naphtho(2,1-b)pyran-3-yl]phenyl]-morpholine,4-[3-(4-methoxyphenyl)-3-phenyl-3H-naphtho(2,1-b)pyran-6-yl]-morpholine,4-[3,3-bis(4-methoxyphenyl)-3H-naphtho(2,1-b)pyran-6-yl]-morpholine,4-[3-phenyl-3-[4-(1-piperidyl)phenyl]-3H-naphtho(2,1-b)pyran-6-yl]-morpholine,2,2-diphenyl-2H-naphtho(2,1-b)pyran, or the like.

In one embodiment the photochromic material is maintained in atransparent state when the photochromic material is exposed to externallight with a small amount of ultraviolet (UV) rays or weak brightness,such as light during the nighttime or indoor light. In addition, thephotochromic material is discolored and changed to an opaque state whenthe photochromic material is exposed to external light with a greatamount of UV rays or strong brightness, such as sunlight. In addition,the photochromic material is reversibly changed to the transparent stateor the opaque state.

The wire grids 21 may be formed of a resin containing the photochromicmaterial as a dye, and may be formed on the substrate 1 by patterningthe resin.

As shown in the embodiment illustrated in FIG. 2, the wire grids 21 areformed as a single layer, but this is not required. The wire grids 21may further include a transparent material layer formed on or below alayer containing a photochromic material.

In one embodiment the wire grids 21 are formed by appropriatelyselecting the photochromic material so that the wire grids 21 may bediscolored under sunlight, and may be maintained in a transparent stateunder indoor light or dark conditions such as at night.

The phase retardation layer 3 illustrated in FIG. 1 is formed on thelinear polarization layer 2 including the wire grids 21.

The phase retardation layer 3 may have double refractioncharacteristics.

Thus, according to the present embodiment, the phase retardation layer 3may be formed of any material having double refraction characteristics,or any material formed by introducing double refraction characteristicsto a material without double refraction characteristics.

Double refraction characteristics may be introduced to a materialwithout double refraction characteristics by growing an alkali metaloxide having great polarisability in a direction parallel to an inclineddirection of a crystal of the alkali metal oxide. In this case, thealkali metal oxide may be CaO and/or BaO.

That is, inclined crystal growth may be performed by depositing thealkali metal oxide on the substrate 1, on which the linear polarizationlayer 2 is formed, so as to be inclined in a direction perpendicular tothe substrate 1 at a preselected or predetermined angle. The preselectedor predetermined angle may be about 50 to about 80 degrees.

In this case and according to one embodiment, when the inclinationcrystal growth is performed at a preselected or predetermined angle of50 degrees or less, growth is not appropriately performed in theinclined direction. In addition, in order to obtain a phase retardationeffect and according to another embodiment, the preselected orpredetermined angle is about 80 degrees or less. In one embodiment, ifthe preselected or predetermined angle exceeds 80 degrees, a phaseretardation effect is reduced.

The phase retardation layer 3 formed of CaO and/or BaO by using theinclination crystal growth may be a half-wave plate or a quarter-waveplate according to the thickness of the phase retardation layer 3.

If the phase retardation layer 3 is formed of CaO, and in a thickness ofabout 2 to about 5 μm, the phase retardation layer 3 may be aquarter-wave plate. In addition, when the phase retardation layer 3 isformed in a thickness of about 4 to about 10 μm, the phase retardationlayer 3 may be a half-wave plate. When the phase retardation layer 3 isa combination of a quarter-wave plate and a half-wave plate, modes forright circular polarization and left circular polarization may be freelyset, and an angle for linear polarization may be set.

If the phase retardation layer 3 is formed of CaO and/or BaO, and thephase retardation layer 3 is used in an organic light-emitting displayapparatus, the phase retardation layer 3 may also perform as a moistureabsorption layer due to the moisture absorption characteristics thereof.

As such, when the alkali metal oxide is deposited so as to be inclinedwith respect to a surface of the linear polarization layer 2, the phaseretardation layer 3 is configured so that a plurality of fine columnsare formed on the linear polarization layer 2 so as to be inclined withrespect to a surface of the linear polarization layer 2.

The linear polarization layer 2 and the phase retardation layer 3 may beformed by using various suitable methods. In addition, the linearpolarization layer 2 and the phase retardation layer 3 may also beapplied to any embodiments of the present invention.

FIG. 3 is a cross-sectional view of a bottom-emission type organiclight-emitting display apparatus according to another embodiment of thepresent invention. In FIG. 3, the linear polarization layer 2 is on asurface of the substrate 1, which faces outside the substrate 1, and thephase retardation layer 3 is on another surface of the substrate 1. Theorganic light-emitting device 5 is on the phase retardation layer 3. Thedescriptions of elements already described will not be repeated. Also inthe bottom-emission type organic light-emitting display apparatus ofFIG. 3, a photochromic material is discolored to exhibit linearpolarization characteristics when the photochromic material is exposedto sunlight. In this case, external light from outside of the substrate1 is converted into linearly polarized light that is polarized in adirection parallel to a transmission-axis direction while transmittingthrough the linear polarization layer 2, and is converted intocircularly polarized light that rotates in one direction whiletransmitting through the substrate 1 and the phase retardation layer 3.Then, after the external light is reflected by the second electrodelayer 53, the external light is converted into circularly polarizedlight that rotates in an opposite direction. The circularly polarizedlight that rotates in the opposite direction is converted into linearlypolarized light that is polarized in a direction perpendicular to atransmission-axis direction while transmitting through the phaseretardation layer 3. The linearly polarized light is not transmittedthrough the linear polarization layer 2, and thus reflected externallight may not be viewed below the lower portion of the substrate 1.

In addition, since the linear polarization layer 2 becomes transparentindoors, the light absorption of the linear polarization layer 2 isreduced, and thus the combination of the linear polarization layer 2 andthe phase retardation layer 3 does not form the circular polarization,thereby preventing or limiting a reduction in the brightness of theorganic light-emitting display apparatus.

FIG. 4 is a cross-sectional view of a bottom-emission type organiclight-emitting display apparatus according to another embodiment of thepresent invention. In FIG. 4, the phase retardation layer 3 and thelinear polarization layer 2 are sequentially arranged in the statedorder on a surface of the substrate 1, which faces outside the substrate1, and the organic light-emitting device 5 is on another surface of thesubstrate 1. The descriptions of elements already described will not berepeated. Also in the bottom-emission type organic light-emittingdisplay apparatus of FIG. 4, external light may be prevented or reducedfrom being reflected, thereby increasing the contrast of thebottom-emission type organic light-emitting display apparatus.

So far, examples of a bottom-emission type organic light-emittingdisplay apparatus that realizes an image in a direction towards thesubstrate 1 have been described, but embodiments of the presentinvention are not limited thereto. Thus, the above-describeddescriptions may also be applied to a top-emission type organiclight-emitting display apparatus that realizes an image emitted from theemissive layer 52 in an opposite direction to the substrate 1, i.e., notin a direction towards the substrate 1.

FIG. 5 is a cross-sectional view of a top-emission type organiclight-emitting display apparatus according to another embodiment of thepresent invention. In FIG. 5, a reflective layer 54 is on the substrate1, and the organic light-emitting device 5 is on the reflective layer54. A sealing member for sealing the organic light-emitting device 5from the outside may be on the organic light-emitting device 5.

Like in the above-described embodiments, the substrate 1 may be atransparent glass substrate, but the substrate 1 does not have to betransparent. In addition, the substrate 1 may be formed of a plasticmaterial or a metal material, in addition to glass. When the substrate 1is formed of metal, an insulating layer is on the substrate 1.

The reflective layer 54 on the substrate 1 may be silver (Ag), magnesium(Mg), aluminum (Al), platinum (Pt), palladium (Pd), gold (Au), nickel(Ni), neodymium (Nd), iridium (Ir), and/or chromium (Cr). The firstelectrode layer 51 may be on the reflective layer 54, and may be formedof an oxide having a high work function, such as ITO, IZO, ZnO, and/orIn₂O₃. In this case, the first electrode layer 51 functions as an anode.If the first electrode layer 51 functions as a cathode, the firstelectrode layer 51 is formed of a material selected from the groupconsisting of Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr and combinationsthereof so as to also perform a function of the reflective layer 54.Hereinafter, a case where the first electrode layer 51 functions as ananode will be described in more detail.

The second electrode layer 53 may be formed as a transparent electrode.In addition, when the second electrode layer 53 is formed as asemi-transparent layer, the second electrode layer 53 may be formed of ametal having a low work function, for example, a material selected fromthe group consisting of lithium (Li) calcium (Ca), LiF/Ca, LiF/Al, Al,Mg, Ag, and combinations thereof, and may be formed to be thin. Also,issues associated with an increased resistance due to a small thicknessmay be addressed by forming a transparent conductor, such as ITO, IZO,ZnO, and/or In₂O₃, on the semi-transparent layer.

The emissive layer 52 interposed between the first electrode layer 51and the second electrode layer 53 is the same as in the above-describedembodiments.

According to the present embodiment, the phase retardation layer 3 andthe linear polarization layer 2 are sequentially arranged in the statedorder on the second electrode layer 53.

Thus, external light from a direction in which an image is realized,that is, external light from above the top-emission type organiclight-emitting display apparatus of FIG. 5 is sequentially transmittedthrough the linear polarization layer 2 and the phase retardation layer3, and then is reflected on each layer of the organic light-emittingdevice 5 or the reflective layer 54. In this case, the external lightmay not be transmitted through the linear polarization layer 2 and thephase retardation layer 3. This principle is the same as in theabove-described embodiments, and thus a detailed description thereofwill not be provided again.

A protective layer 6 may be on the second electrode layer 53, and thenthe phase retardation layer 3 and the linear polarization layer 2 may beon the protective layer 6, as shown in FIG. 6.

The protective layer 6 may prevent or protect the second electrode layer53 from being damaged during sputtering for forming the phaseretardation layer 3, and may be formed of a transparent inorganic ororganic material.

The inorganic material may be a metal oxide, a metal nitride, a metalcarbide, and/or a metal oxynitride. The metal oxide may be a siliconoxide, an aluminium oxide, a titanium oxide, an indium oxide, a tinoxide, and/or an indium tin oxide. The metal nitride may be an aluminiumnitride, and/or a silicon nitride. The metal carbide may be a siliconcarbide, and the metal oxynitride may be a silicon oxynitride. Theinorganic material may be silicon, and may be a ceramic derivative ofsilicon and/or metal. In addition, the inorganic material may bediamond-like carbon (DLC), or the like.

The organic material may be an organic polymer, an inorganic polymer, anorganometallic polymer, and/or a hybrid organic/inorganic polymer,and/or may be an acryl resin.

Although not illustrated, the protective layer 6 may be between thephase retardation layer 3 and the linear polarization layer 2, oralternatively, may be on the linear polarization layer 2.

FIG. 7 is a cross-sectional view of a top-emission type organiclight-emitting display apparatus according to another embodiment of thepresent invention. The top-emission type organic light-emitting displayapparatus of FIG. 7 is manufactured by further forming a film-typesealing member 7 on the linear polarization layer 2 of the top-emissiontype organic light-emitting display apparatus of FIG. 6.

The film-type sealing member 7 protects the organic light-emittingdevice 5 from external moisture and oxygen. The film-type sealing member7 includes an inorganic layer 71 and/or an organic layer 72, and may beformed by alternately stacking the inorganic layer 71 and the organiclayer 72. The remaining configuration is the same as in theabove-described embodiments, and a detailed description thereof will notbe provided again.

The inorganic layer 71 may be formed of a metal oxide, a metal nitride,a metal carbide, and/or a metal oxynitride. The metal oxide may be asilicon oxide, an aluminium oxide, a titanium oxide, an indium oxide, atin oxide, and/or an indium tin oxide. The metal nitride may be analuminium nitride and/or a silicon nitride. The metal carbide may be asilicon carbide, and the metal oxynitride may be a silicon oxynitride.Silicon may be used as an inorganic material, and a ceramic derivativeof silicon and/or metal may be used. In addition, DLC may be used.

The inorganic layer 71 may be formed by using a suitable depositionmethod. In this case, an air void containing the inorganic layer 71 maybe grown. Thus, to prevent or limit the air void from being grown at thesame location, the organic layer 72 may be further formed in addition tothe inorganic layer 71. The organic layer 72 may be an organic polymer,an inorganic polymer, an organometallic polymer, and/or a hybridorganic/inorganic polymer, and/or may be an acryl resin.

In FIG. 7, the inorganic layer 71, the organic layer 72, and theinorganic layer 71 are sequentially stacked in the stated order on thelinear polarization layer 2, but embodiments of the present inventionare not limited thereto. For example, the organic layer 72, theinorganic layer 71, and the organic layer 72 may be sequentiallystacked, or a plurality of layers of the organic layer 72, the inorganiclayer 71, and the organic layer 72 may be stacked. The film-type sealingmember 7 may be applied not only to FIG. 7, but also to otherembodiments of the present invention.

FIG. 8 is a cross-sectional view of a top-emission type organiclight-emitting display apparatus according to another embodiment of thepresent invention. In FIG. 8, the phase retardation layer 3 and thelinear polarization layer 2 are between the reflective layer 54 and theorganic light-emitting device 5. External light from a directionindicated by the smaller arrows is converted into linearly polarizedlight that is polarized in a direction parallel to a transmission-axisdirection while transmitting through the linear polarization layer 2,and is converted into circularly polarized light that rotates in onedirection while transmitting through the phase retardation layer 3.Then, after the external light is reflected by the reflective layer 54,the external light is converted into circularly polarized light thatrotates in an opposite direction. The circularly polarized light thatrotates in the opposite direction is converted into linearly polarizedlight that is polarized in a direction perpendicular to atransmission-axis direction while transmitting through the phaseretardation layer 3. The linearly polarized light is not transmittedthrough the linear polarization layer 2, and thus reflected externallight may not be viewed above the upper portion of the substrate 1.

Alternatively, although not illustrated, the phase retardation layer 3may be formed on the reflective layer 54, the organic light-emittingdevice 5 may be formed on the phase retardation layer 3, and then thelinear polarization layer 2 may be formed on the organic light-emittingdevice 5.

FIG. 9 is a cross-sectional view of a top-emission type organiclight-emitting display apparatus according to another embodiment of thepresent invention, and illustrates a case where a transparent substrateis used as the sealing member 7.

The transparent substrate may be a glass substrate, but is not limitedthereto. For example, the transparent substrate may be a plasticsubstrate.

According to the present embodiment, the phase retardation layer 3 andthe linear polarization layer 2 are sequentially arranged in the statedorder on an upper surface of the sealing member 7, that is, a surface ofthe sealing member 7, which faces outwards.

FIG. 10 is a cross-sectional view of a top-emission type organiclight-emitting display apparatus according to another embodiment of thepresent invention. In FIG. 10, the phase retardation layer 3 is on onesurface of the transparent substrate as the sealing member 7, whichfaces the organic light-emitting device 5. In addition, the linearpolarization layer 2 is on an opposite surface of the sealing member 7.FIG. 11 is a cross-sectional view of a top-emission type organiclight-emitting display apparatus according to another embodiment of thepresent invention. In FIG. 11, the linear polarization layer 2 and thephase retardation layer 3 are sequentially arranged in the stated orderon a surface of the transparent substrate as the sealing member 7, whichfaces the organic light-emitting device 5.

Also, in the top-emission type organic light-emitting displayapparatuses of FIGS. 5 through 11, the linear polarization layer 2 islocated to be close to an external light source, compared to the phaseretardation layer 3, and the phase retardation layer 3 is below thelinear polarization layer 2, thereby preventing or reducing externallight from being reflected according to the above-described principle.

In the top-emission type organic light-emitting display apparatuses ofFIGS. 9 through 11, although not illustrated, inert gas may be filledbetween the sealing member 7 and the organic light-emitting device 5,and an organic or inorganic material may be therebetween, therebyfurther improving the sealing characteristics of the organiclight-emitting device 5.

FIG. 12 is a cross-sectional view of a bottom-emission type organiclight-emitting display apparatus of an active matrix (AM) type,according to another embodiment of the present invention.

Referring to FIG. 12, a thin film transistor (TFT) is on the substrate1. At least one TFT is on every pixel, and is electrically connected tothe organic light-emitting device 5.

In more detail, a buffer layer 31 is on the substrate 1, and asemiconductor active layer 32 having a preselected or predeterminedpattern is on the buffer layer 31. A gate insulating layer 33 formed ofSiO₂ or SiN_(x) is on the semiconductor active layer 32, and a gateelectrode 34 is on a preselected or predetermined region of the gateinsulating layer 33. The gate electrode 34 is connected to a gate linefor applying a TFT on/off signal. An interlayer insulating layer 35 ison the gate electrode 34. Source/drain electrodes 37 and 36 are formedso as to contact source/drain regions of the semiconductor active layer32 through contact holes, respectively.

The TFT formed as described above is covered and protected by apassivation layer 21. In FIG. 12, the passivation layer 29 is formed bysequentially stacking the linear polarization layer 2 and the phaseretardation layer 3.

The first electrode layer 51, which functions as an anode, is on thephase retardation layer 3, and a pixel define layer 56 is formed so asto cover the first electrode layer 51. An opening is formed in the pixeldefine layer 56, and the emissive layer 52 is formed in a region definedby the opening. Then, the second electrode layer 53 is formed so as tocover all the pixels.

Also in the bottom-emission type organic light-emitting displayapparatus of an AM type, since the linear polarization layer 2 and thephase retardation layer 3 are sequentially stacked in the stated orderon the TFT, the linear polarization layer 2 and the phase retardationlayer 3 may prevent or reduce external light from below thebottom-emission type organic light-emitting display apparatus from beingreflected.

As shown in FIG. 13, a passivation layer 38 formed of an organicmaterial and/or an inorganic material may be on the TFT, and the linearpolarization layer 2 and the phase retardation layer 3 may besequentially arranged in the stated order on the passivation layer 38.

In the bottom-emission type organic light-emitting display apparatus ofan AM type, as long as the linear polarization layer 2 is located so asto be relatively close to an external light source, and the phaseretardation layer 3 is located so as to be relatively close to theorganic light-emitting device 5, the linear polarization layer 2 and thephase retardation layer 3 may be on any surfaces of the substrate 1, theTFT, and/or the organic light-emitting device 5. That is, although notillustrated, the phase retardation layer 3 and the linear polarizationlayer 2 are on one side and/or the other side of the substrate, as shownin FIGS. 1, 3 and 4, and then the TFT and the organic light-emittingdevice 5 may be on the phase retardation layer 3 and the linearpolarization layer 2, or alternatively, the phase retardation layer 3and/or the linear polarization layer 2 may be between layersconstituting the TFT.

FIG. 14 is a cross-sectional view of a top-emission type organiclight-emitting display apparatus of an AM type, according to anotherembodiment of the present invention.

Referring to FIG. 14, the TFT is on the substrate 1. At least one TFT ison every pixel, and is electrically connected to the organiclight-emitting device 5. The structure of the TFT is the same as in FIG.12, and thus a detailed description thereof will not be provided again.

As shown in FIG. 14, a passivation layer 38 is formed so as to cover theTFT, and the reflective layer 54 is on the passivation layer 38. Thefirst electrode layer 51, functioning as an anode, is on the reflectivelayer 54, and the pixel define layer 56, which is formed of aninsulating material, is formed so as to cover the first electrode layer51. An opening is formed in the pixel define layer 56, and the emissivelayer 52 is formed in a region defined by the opening. Then, the secondelectrode layer 53 is formed so as to cover all the pixels.

In FIG. 14, the linear polarization layer 2 and the phase retardationlayer 3 are sequentially arranged in the stated order on a surface of asubstrate as the sealing member 7, which faces the organiclight-emitting device 5, like in FIG. 11. Thus, the linear polarizationlayer 2 and the phase retardation layer 3 may prevent or reduce externallight from above the top-emission type organic light-emitting displayapparatus of FIG. 14 from being reflected.

Although not illustrated, the configurations of FIGS. 5 and 10 may alsobe applied to such AM type organic light-emitting display apparatuses.

While the present invention has been described in connection withcertain exemplary embodiments, it is to be understood that the inventionis not limited to the disclosed embodiments, but, on the contrary, isintended to cover various modifications and equivalent arrangementsincluded within the spirit and scope of the appended claims, andequivalents thereof.

What is claimed is:
 1. An organic light-emitting display apparatuscomprising: a substrate; an organic light-emitting device on thesubstrate; a sealing member on the organic light-emitting device; aphase retardation layer on a surface of the sealing member; and a linearpolarization layer on another surface of the sealing member, or thephase retardation layer, wherein the linear polarization layer islocated to be closer to a source of external light than the phaseretardation layer, and wherein the linear polarization layer comprises aphotochromic material.
 2. The organic light-emitting display apparatusof claim 1, wherein the phase retardation layer is on the organiclight-emitting device, and wherein the linear polarization layer is onthe phase retardation layer.
 3. The organic light-emitting displayapparatus of claim 1, wherein the sealing member is a transparentsubstrate, and wherein the phase retardation layer and the linearpolarization layer are sequentially arranged in the stated order on thesurface of the sealing member opposite to the surface of the sealingmember, which faces the organic light-emitting device.
 4. The organiclight-emitting display apparatus of claim 1, wherein the sealing memberis a transparent substrate, wherein the phase retardation layer is onthe surface of the sealing member, which faces the organiclight-emitting device, and wherein the linear polarization layer is onthe surface of the sealing member opposite to the surface of the sealingmember, on which the phase retardation layer is formed.
 5. The organiclight-emitting display apparatus of claim 1, wherein the sealing memberis a transparent substrate, wherein the linear polarization layer is onthe surface of the sealing member, which faces the organiclight-emitting device, and wherein the phase retardation layer is on asurface of the linear polarization layer, which faces the organiclight-emitting device.
 6. The organic light-emitting display apparatusof claim 1, wherein the phase retardation layer comprises a quarter-waveplate or a half-wave plate.
 7. The organic light-emitting displayapparatus of claim 1, wherein the linear polarization layer comprises aplurality of wire grids that are spaced apart from each other.